Cavity optomechanics focuses on the interaction between confined light and a mechanical degree of freedom. Vibrational modes of superﬂuid helium-4 have recently been identified as an attractive mechanical element for cavity optomechanics, thanks to their ultra-low dissipation arising from superfluid’s viscosity-free flow. Our approach to superﬂuid optomechanics is based on nanometer-thick films of superﬂuid helium which self-assemble on the surface of a microscale optical whispering gallery mode resonator inside our cryostat. Excitations within the ﬁlm, known as third sound, manifest as surface thickness waves with a restoring force provided by the van der Waals interaction. These excitations then dispersively couple to the light confined inside the optical resonator. Using this optomechanical coupling mechanism, we experimentally probed the thermodynamics of these superfluid excitations in real-time, and demonstrated, for the first time, both laser cooling and amplification of the superfluid thermal motion. While lasers are widely used to cool gases and solid objects, they have never before been applied to cool a quantum liquid.
Our research efforts are currently focused on developing new devices with greatly enhanced optomechanical performance (with single photon cooperativities C0 well in excess of unity), which will serve as probes of superfluid helium physics of unprecedented sensitivity. Our goals also include exploring the rich interaction between quantized vortices and third sound phonons and investigating thin-film superfluid inertial sensing directly on silicon chips.
- “Laser cooling and control of excitations in superfluid helium,” Nature Physics, 12, 8, 788, 2016. (pdf)
- “Microphotonic Forces from Superfluid Flow,” Physical Review X, 6, 2, 21012, 2016. (pdf)
- “Theoretical framework for thin film superfluid optomechanics: towards the quantum regime,” New Journal of Physics, 18, 12, 123025, 2016. (pdf)
This research aims to create interfaces between light and electronics, through their common interaction with a mechanical element. Such interfaces can be used to integrate quantum photonic systems with quantum superconducting circuits in future quantum information devices, for improved on-chip clocks and receivers for mobile communications that benefit from laser control and measurement, and for scalable photonic circuitry and photonic links in next generation computer chips, among other applications. Recent work:
- “Free spectral range electrical tuning of a high quality on-chip microcavity,”
[Arxiv 1808.01908, 2018] (pdf)
- “Injection locking of an electro-optomechanical device,”
Optica, vol. 4, pp. 1196-1204, 2017. (pdf)
- “High bandwidth on-chip capacitive tuning of microtoroid resonators,”
Optics Express, vol. 24, p. 20400, 2016. (pdf)
Selected work includes:
- “Light-Mediated Cascaded Locking Multiple Nano-Optomechanical Oscillators,” Physical Review Letters, vol. 118, p. 063605, 2017. (pdf)
- “Scalable high-precision tuning of photonic resonators by resonant cavity-enhanced photoelectrochemical etching,” Nature Communications, vol. 8, p. 14267, 2017. (pdf)
- “High-frequency nano-optomechanical disk resonators in liquids,” Nature Nanotechnology, vol. 10, pp. 810–816, 2015. (pdf)
- “Photoelastic coupling in gallium arsenide optomechanical disk resonators,” Optics Express, vol. 22, no. 12, pp. 14072–14086, 2014. (pdf)
- “High frequency GaAs nano-optomechanical disk resonator,” Physical Review Letters, vol. 105, no. 26, p. 263903, 2010. (pdf)
Full publication list with supplemental materials available here.